Following is a list of definitions of abbreviations found in the application.    3GPP—Third Generation Preferred Partnership    CN—core network    EHPLMN—equivalent home public land mobile network    EM—element manager    eNB—eNodeB    ePLMN—equivalent public land mobile network    HPLMN—home public land mobile network    HSS—home subscriber server    LTE—long term evolution    MDT—minimization of drive tests    MME—mobility management entity    OA & M—operations, administration, and maintenance    PLMN—public land mobile network    RAN—radio access network    RPLMN—registered PLMN    RSRP—reference signal received power    RSRQ—reference signal received quality    SINR—signal to interference and noise ratio    TCE—trace collection entity    UMTS—Universal Mobile Terrestrial Service
Wireless network operators are strongly motivated to use resources in an efficient way, both in order to maximize their own profit and to provide services to customers at a reasonable price. Network optimization, that is, the placement and configuration of resources so as to maximize the area in which coverage is provided and the quality of service provided by that coverage, contributes greatly to the efficient use of resources. One way in which operators carry out network optimization is through drive testing, in which employees of an operator carry a device, such as a typical user device, through the service area of a network. The device is usually carried in an automobile, and as the employee drives to various points within the service area, the device collects data relating to the quality of the service that is being made available to it. Drive testing is obviously costly, and the unnecessary use of automobiles contributes to air pollution and also presents some measure of personal danger to the employees performing the testing, because the possibility of traffic accidents is always present.
In order to minimize drive testing, operators are more and more turning to mechanisms that take advantage of the fact that customer devices are constantly receiving service in numerous locations throughout their service areas and that receiving information relating to the service experience of multiple devices can substitute for drive testing in many cases and can reduce or eliminate the need for drive testing. Third Generation Preferred Partnership (3GPP) long term evolution (LTE) and universal mobile terrestrial service (UMTS) release 10 includes a feature called “Minimization of Drive Tests” (MDT), which provides the ability for operators to gather information such as radio measurements which are associated with customer UEs and use this information to assist network optimization.
Another mechanism directed to the efficient use of resources is radio access network (RAN) sharing, in which two or more core network operators share a radio access network. Sharing of radio access network resources can reduce duplication of resources while allowing each participating core network operator to serve its customers and to provide features and pricing desired by its customers in comparison to the features and pricing offered by other core network operators sharing the radio access network.